Method for preparing an open porous polymer material and an open porous polymer material

ABSTRACT

The present invention relates to a method for preparing an open pourous polymer material, wherein said method comprises forming or a polymer solution, addition of a porogen to said polymer solution and precipitation with water of polymer from said polymer solution, and said method then comprises removal of solvent and porogen from said polymer material wherein said precipitation is homogenous through that said water is in form of crystal water and that said crystal water is bonded to said porogen, wherein said porogen is a sugar hydrate. It further relates to an open porous polymer material, a mixture comprising a sugar hydrate and a polymer solution. and a designed material, and uses thereof.

FIELD OF INVENTION

[0001] The present invention relates to a method for preparing an openporous polymer material, wherein said method comprises forming of apolymer solution, addition of a porogen to said polymer solution andprecipitation with water of polymer from said polymer solution, and saidmethod then comprises removal of solvent and porogen from said polymermaterial. The present invention further relates to an open porouspolymer material, a mixture which is obtained in said method, a designedmaterial comprising said porous polymer material, and uses of saidporous polymer material, said mixture and said designed material.

[0002] Further, the present invention relates to a mixture comprising asugar hydrate and a polymer solution, and use of said mixture forpreparing a designed material.

PRIOR ART

[0003] It is earlier known to prepare porous polymer material by forminga mixture of a polymer solution and a pore forming filling agent, andthen leaching the filling agent whereupon addition of leach agent alsoprovides for the polymer being in a solid state. An example of such amethod is disclosed in U.S. Pat. No. 4,242,464 which describespreparation of porous material wherein a working material coagulates atthe addition of a leaching agent and the leaching agent is used to leachout particles, e.g. of salt or sugar, from the working material. Afurther method for preparing is described in WO, A2, 9947097 whichrelates to medical implants. These medical implants consist ofbiologically degradable and open porously foam, wherein forming of poresis obtained through the washing out of water soluble particles, e.g.glucose, which are solved in the foam. Further in U.S. Pat. No.3,644,233 is disclosed the use of salts with crystal water for formingof pores when preparing micro porous sheet structures.

[0004] The porous materials which are obtained by the earlier methodsfor preparing suffer from different weaknesses, such as the materialshaving an insufficient and a discontinuous pore structure or thematerial not being suitable for processing. Such weaknesses is a directresult of not being able to satisfactory control the forming of theporous materials in the earlier methods for preparation, wherein themethods for preparation suffer from problems such as inhomogenity,forming of lumps, local precipitations or the like.

DESCRIPTION OF THE INVENTION

[0005] We have developed a new method for preparing an open porouspolymer material, wherein said method comprises homogenous precipitationwith water of a polymer from a polymer solution and wherein the water isadded to said polymer solution in the form of crystal water which isbonded to a porogen, wherein said porogen is a sugar hydrate.

[0006] The present invention relates to a method for preparing an openporous polymer material, wherein said method comprises forming of apolymer solution, addition of a porogen to said polymer solution andprecipitation with water of a polymer from said polymer solution, andsaid method then comprises removal of solvent and porogen from saidpolymer material, wherein said precipitation is homogenous through thatsaid water is in form of crystal water and said crystal water is bondedto said porogen, wherein said porogen is a sugar hydrate.

[0007] By said method an open porous polymer material is obtained, whichpolymer material has internally connected pores, i.e. a continuous porestructure. By adding crystal water which is bonded to a porogen, whereinsaid porogen is a sugar hydrate, it has been shown to be possible toobtain a very homogenous precipitation of said polymer from the polymersolution by using water. Further, it has also been shown that themixture which is formed when said sugar hydrate is added to the polymersolution is tixotropical. Said porogen is a crystalline sugar hydrate,suitably finely grind, which by the contact with the polymer solutiontransforms to a crystal water free crystal modification. At contact withthe polymer solution said porogen thus looses the bonded crystal waterto the solvent and increasing amount of water in the solvent phase makesthe polymer precipitating around added porogen. Further, it takes timefor said porogen to transform to a crystal water free crystalmodification and this time is used to achieve a, as far as possible,homogenous suspension of particles. The time it takes for said porogento transform to a crystal water free crystal modification may becontrolled. In the homogenous suspension of particles the crystalconversion brings about that water is added at the nearest equivalent tohomogenous to the whole polymer solution. Further, it is possible tocontrol the rate by which the polymer precipitates by choosing ratio ofpolymer in the polymer solution and amount of porogen which is added.The open porous polymer material which is obtained by said method isthus homogenous and free from lumps as well as local precipitations.

[0008] Further, the obtained open porous polymer material which isobtained by said method is a homogenous porous solid substance with avery high porosity and internally connected pores.

[0009] By that the obtained open porous polymer material is “a solidsubstance”, is here meant that the open porous polymer material has arigid or stiff structure. The rigid or stiff structure makes the openporous polymer material maintaining its physical structure when thepolymer material is exposed to normal influence.

[0010] For example, a total porosity of above 90% was obtained for theopen porous polymer materials in the examples. Further, it is possibleto clearly see the open pore structure of the open porous polymermaterials in the photographs in FIGS. 1 and 2, which have been takenwith scanning electron microscopy. In FIGS. 1 and 2 it is also possibleto see that the open porous polymer materials internally have a fibrousstructure of internally connected pores with high porosity. The openpore structure is also supported by the fact that no inclusions of sugaror solvent is present in the open porous polymer materials. Further, itis also shown that casted thin films have the same pore morphology ascasted thick cast bodies.

[0011] Said open porous polymer material which is obtained by saidmethod has by, e.g., being homogenous and free from lumps as well aslocal precipitations, its rigid or stiff structure, and the feature ofmaintaining its physical structure, thus been shown to be an open porouspolymer material of a very good quality in spite of the very highporosity and the internally connected pores of the open porous polymermaterial.

[0012] When the crystal conversion has run for a while the mixture,which is formed when said porogen with bonded crystal water is added tosaid polymer solution, is stabilised by the precipitation of polymer anda gel is formed. The gelling of the mixture is of great practical use,because the gelled mixture, and thus the polymer material, may be formedwithout that, e.g., final porosity or rigidity of the polymer materialis influenced. The tixotropical features of the gelled mixture makes itadvantageous to let the mixture gel before casting with it, and thetixotropical features are very suitable when casting thick cast bodies.Further, the stabilised gelled mixture, which is a heterogeneous mixtureand thus not yet contain any pores, is suitable to be designed by forexample three dimensional casting or further processing, for example byinjection moulding, moulding, extrusion, coating, calendering or thelike, or further methods which may be used in connection withthermoplasts. When the stabilised mixture is designed or formed to adesired form the solvent and the porogen are removed, for example by theaddition of water, wherein a phase inversion is achieved and the porestructure is formed. When solvent and porogen are removed by addition ofwater, the water may suitably be pressed through the porous structure ofthe stabilised mixture, and thereupon all rests of solvent and porogenare removed. An open porous polymer material with an open communicatingcell network is thus formed. The open porous polymer material may thenbe dried. The size of pores of the open porous polymer material may becontrolled by choosing particle size of the porogen and concentration ofpolymer in the polymer solution. By varying the amount of sugar hydrate,the size of crystals of sugar hydrate and the ratio of polymer, thegelling time, and also the porosity and rigidity for the final polymermaterial, may be controlled.

[0013] Further, it is also possible by said method to in advance controlwhat features the open porous polymer material should have by choosingwhich sugar hydrate that should be porogen, the size of the particles ofthe porogen, the amount of porogen, the amount of crystal water, thepolymer and/or the ratio of polymer in the polymer solution.

[0014] Said polymer may for example be polyurethane, polyurethaneurea orpolyurea. Further, the solvent which should be soluble in water, ischosen depending, among other, on choice of polymer and may for examplebe dimethylformamide (DMF), dimethylacetamide (DMAC),N-methylpyrrolidone (NMP), or dimethylsulfoxide (DMSO).

[0015] Said porogen is chosen from sugar hydrates, and should be solublein water but not soluble in the solvent which solves said polymer.Further, said porogen forms crystals with crystal water, and saidporogen is a sugar hydrate, for example a sugar monohydrate or a sugardihydrate, for example glucose monohydrate or maltose monohydrate.

[0016] As is earlier described said solvent and porogen may for examplebe removed by the addition of water, wherein a phase inversion isachieved and the pore structure is formed.

[0017] Further, said method comprises the forming of a mixture by addingsaid porogen with bonded crystal water to said polymer solution, whichmay for example be done during fast stirring, or the like. Said mixtureis a tixotropical mixture. In the same way as it is possible to controlin advance which features the open porous polymer material should have,it is also possible to influence the features of said mixture, forexample the viscosity, by choosing which sugar hydrate that should beporogen, the particle size of the porogen, the amount of porogen, theamount of crystal water, the polymer and/or the ratio of polymer in thepolymer solution.

[0018] A further embodiment according to the present invention relatesto said method for preparing, wherein a tixotropical mixture is formedat the addition of said sugar hydrate to said polymer solution.

[0019] Still a further embodiment according to the present inventionrelates to said method for preparing, wherein said removal of solventand porogen is achieved by using water. The water which is used for saidremoval may for example contain any form of conditioning agent, forexample, ethanol, zinc or the like.

[0020] A further embodiment according to the present invention relatesto said method for preparing, wherein said polymer is a polyurethane,polyurethaneurea or polyurea.

[0021] Even a further embodiment according to the present inventionrelates to said method for preparing, wherein said sugar hydrate is asugar monohydrate, for example glucose monohydrate or maltosemonohydrate, or a sugar dihydrate, or the like.

[0022] Still a further embodiment according to the present inventionrelates to said method, wherein said polymer is biologically degradable.Said polymer may be biologically degradable by containing such an amountof ester groups that the polymer by hydrolysis or during enzymaticinfluence is degraded to such an extent that it looses mechanicalproperties, is secreted or metabolised. By choosing polymer, an openporous polymer material, which has degrading times varying from a fewmonths to several years, may be obtained.

[0023] Still a further embodiment according to the present inventionrelates to said method, wherein said method comprises design of thestabilised mixture, which stabilised mixture is formed when said porogenwith bonded crystal water is added to said polymer solution. Said designshall be regarded in its broadest context and may for example be a threedimensional casting or a further processing, for example by injectionmoulding, moulding, pressing, extrusion, coating, calendering. Further,said design may be achieved with methods which demand differentviscosities of said mixture. By choosing which sugar hydrate that shouldbe the porogen, the particle size of the porogen, the amount of porogen,the amount of crystal water, the polymer and/or the ratio of polymer inthe polymer solution, said mixture may be able to gel at differentrates. By these choices it is also possible to control the very usefulfeature of keeping the form after gelling. Said mixture has shown tohave this feature, and to which extent the mixture maintains or keepsthe form may be adapted after desire.

[0024] The present invention also relates to an open porous polymermaterial, wherein said porous polymer material may be prepared by amethod as described herein.

[0025] An embodiment according to the present invention relates to anopen porous polymer material, wherein said porous polymer material hasan open continuous pore structure.

[0026] A further embodiment according to the present invention relatesto an open porous polymer material, wherein said porous polymer materialhas an open communicating cell network.

[0027] Still a further embodiment according to the present inventionrelates to an open porous polymer material, wherein said porous polymermaterial is homogenous and free from lumps as well as localprecipitations.

[0028] A further embodiment according to the present invention relatesto an open porous polymer material, wherein said porous polymer materialhas a rigid or stiff structure.

[0029] An embodiment according to the present invention relates to anopen porous polymer material, wherein said porous polymer material has atotal porosity of above 90%.

[0030] Still a further embodiment according to the present inventionrelates to an open porous polymer material, wherein said porous polymermaterial may be of polyurethane, polyurethaneurea or polyurea.

[0031] In still a further embodiment said open porous polymer materialcomprises secondary functional groups for covalent chemical bonding, forexample secondary hydroxyl, amine, carboxyl and/or thienyl groups,wherein to which functional groups biologically active substances maybe, reversible or irreversible, covalently bonded. Examples of openporous polymer materials which comprises secondary functional groups maybe found in Swedish patent application SE, A, 0004924-7, which patentapplication hereby is referred to as a whole.

[0032] In still a further embodiment said open porous polymer materialcomprises a polymer with hydrolysable ester groups. Further, said openporous polymer material may comprise a polymer having ester groups atsuch a distance from each other that after hydrolysis of said estergroups, fragments are obtained that are less than 2000 Dalton, whereinsaid fragments may be secreted out from a human or animal body.Preferably the obtained fragments may be less than 1000 Dalton.

[0033] The present invention further relates to a mixture comprisingsaid sugar hydrate and said polymer solution. Said mixture, which is aheterogeneous mixture and does not yet contain any pores, is stabilised,when said sugar hydrate which has bonded crystal water is added to saidpolymer solution, by the precipitation of the polymer and the forming ofgel. Also, said mixture is a tixotropical mixture. Further, said mixtureis comprised in a method which is described herein.

[0034] The present invention also relates to a designed material, whichhas been designed or processed as described earlier, which designedmaterial may be for example films, moulded or casted bodies, implants,pipes, or the like. Said designed material comprises an open porouspolymer material which has been described herein. Further said designedmaterial may be biologically degradable inside or in contact with ahuman or animal body by that said polymer may be biologically degradableas described earlier. By choosing polymer a designed material havingdegrading times which may vary from a few months to several years may beobtained.

[0035] A further embodiment relates to said designed material, whereinthe thickness of the material may be varied from the thickness of a thinfilm to a thickness of up to 10 cm.

[0036] Because of the tixotropical feature of the mixture the mixturemay at design of the open porous polymer material be poured to athickness which may be varied from the thickness of thin film to thethickness of up to 10 cm, i.e. thin films as well as cast bodies with athickness of up to 10 cm and everything there between may be obtained.

[0037] Further the present invention relates to use of an open porouspolymer material, which is described herein, as for example film,moulded bodies, implants, pipes, or the like. Said open porous polymermaterial may be used as filling in, for example bones, such as discs,synthetic bone replacement, for example in the form of granules forreplacement of bone tissue, meniscus or the like, or as pipes, forexample, for replacement of blood vessels, guidance forgrowth/regeneration of tendons and/or nerves, or other biologicaltissue, or in connection with treatment of wounds as carrier ofdressings for wound healing, growth factors or the like, artificialskin, or as matrix/scaffold for, for example: stem cells, fibroblasts,osteoblasts, osteocytes, chondroblasts, chondrocytes among other, aswell as autogenous, allogenous and xenogenous, or as matrix/scaffold forgrowth/regeneration of tissues, for example, tendons and/or nerves, orother biological tissue.

[0038] Said use also relates to an open porous polymer material obtainedby a method which is described herein, and the designed material whichis described herein.

[0039] Ideally, a matrix/scaffold for tissue proliferation (or growth)or regeneration should have the following characteristics; (i)three-dimensional and highly porous with an interconnected pore networkfor cell growth and flow transport of nutrients and metabolic waste;(ii) biocompatible and bioresorbable with a controllable degradation andresorption rate to match cell/tissue ingrowth in vitro and/or in vivo;(iii) suitable surface chemistry for cell attachment, proliferation anddifferentiation and (iv) mechanical properties to match those of thetissues at the site of implantation.

[0040] The present invention also relates to use of a mixture which isdescribed herein for preparing a designed material, wherein saiddesigned material may be as described herein.

[0041] Example which describes, but by no means limits, the invention isdisclosed below.

DESCRIPTION OF FIGURES

[0042]FIG. 1 shows a photograph of an open porous polymer material whichhas been taken by use of scanning electron microscopy, wherein 1.0 cm inthe photograph corresponds to 14.8 μm open porous polymer material.

[0043]FIG. 2 shows a photograph of an open porous polymer material whichhas been taken by use of scanning electron microscopy, wherein 1.0 cm inthe photograph corresponds to 14.8 μm open porous polymer material.

EXAMPLES Materials and Methods

[0044] Glucose-monohydrate was obtained from Applichem, Darmstadt,Germany and was of bio-grade quality. DMF (anhydroscan) was obtainedfrom LAB SCAN, Dublin, Ireland and was of HPLC quality. MDI was obtainedfrom Bayer AG, Leverkusen, Germany and the polycaprolacton diol wasobtained from Solvay Interox LTD, Warrington, England. All otherchemicals were obtained from Sigma-Aldrich-Fluka and were of analyticalreagent quality.

[0045] NMR spectra were recorded on a Varian VH 300 MHz instrument. Thecontent of sulphur was analysed on a LECO SC-432 Sulphur Analyzer atMikro Kemi AB in Uppsala, Sweden.

Example 1 Preparation of an Open Porous Polymer Material

[0046] a) Preparation of Polymer

[0047] A pre-polymer was prepared by reacting polycaprolactondiole[M_(n)=530] with diphenylmetandiisocyanate (MDI) [NCO:OH]=2:1]. Apolymer (fibre polymer) was prepared by chain extension of thepre-polymer with 1,3-diaminopropane. The molecular weight of the fibrepolymer was estimated with SEC (“Size Exclusion Chromatography”) inDMF-LiCI against PEO standards and was found to be 113000.

[0048] b) Preparation of an Open Porous Polymer Material

[0049] 100 g of a fibre polymer of polyurethaneurea (9% by weight) whichwas dissolved in DMF was added to 75 g glucosemonohydrate, and thecomponents were mixed fastly for about 30 seconds. Here the unsievedglucosemonohydrate with an approximate particle size of 0-600 μm wasused. The mixture of low viscosity that was obtained was casted to athin film with a thickness of 2 mm. Then the film was allowed to gel.When further 2 minutes had passed the mixture started to be thick andafter 2.5 minutes the mixture was poured on to a glass plate to athickness of 5-7 cm, i.e. a cast body with a thickness of 5-7 cm wasobtained. The mixture did have such a thick consistence that it did notflow anymore, instead it maintained its form. When more than 3 minuteshad passed the mixture had gelled, i.e. the polymer had precipitated,completely. Both cast samples of the open porous polymer material, i.e.the film and the cast body, were allowed to rest for about 10 minutesbefore they were put into lukewarm water (about 40° C.). The film couldimmediately be separated from the glass plate. The cast body was allowedto stay in water until the next day, i.e. about 24 hours, wherein itcould be kneaded for removal of remaining enclosed sugar.

[0050]FIG. 1 shows a photograph which has been taken by use of scanningelectron microscopy, which shows the size of the pores in an open porouspolymer material in example 1, and 1.0 cm in the photograph correspondsto 14.8 μm of open porous polymer material. The open porous polymermaterials in example 1 did lack enclosed glucose and DMF, which wasshown with ¹H NMR.

Example 2 Preparation of an Open Porous Polymer Material

[0051] The fibre polymer was prepared according to example 1 a). Thenfurther, in the same way as in example 1, 100 g of a fibre polymer ofpolyurethaneurea (12% by weight) dissolved in DMF and 75 gglucosemonohydrate. The glucosemonohydrate was here sieved to a size ofparticles of between 150-250 μm. Here the mixture gelled faster ascompared to in example 1. The size of the pores will be less for an openporous polymer material in example 2 as the particles of sugar are less,see FIG. 2. The open porous polymer material in example 2 will also bemore rigid because the ratio of polymers is greater in the solution. Ifan even faster gelling is desired it is possible to increase the ratioof polymer to, for example, 18% by weight. This increase will also givea further rigidity to the resulting open porous polymer material.

[0052]FIG. 2 shows a photograph which has been taken by use of scanningelectron microscopy, which shows the size of the pores in an open porouspolymer material in example 2, and 1.0 cm in the photograph correspondsto 14.8 pm of open porous polymer material. The open porous polymermaterials in example 2 did lack enclosed glucose and DMF, which wasshown with ¹H NMR.

[0053] In examples 1 and 2 open porous polymer materials were obtainedhaving almost 100% continuous open pore structures. There were also noinclusions of glucose or dimethylformamide in the open porous polymermaterials. The open structure of pores is also supported of thephotographs in FIGS. 1 and 2, which have been taken by use of scanningelectron microscopy. The total porosity for the open porous polymermaterials is also very high, i.e. over 90% in both examples 1 and 2. Theporosity in an open porous polymer material may be estimated bymeasuring of void volume and calculation of the volume of a symmetricsample with a known weight. Further it was also shown that casted thinfilms had the same morphology of pores as casted thick cast bodies, forexample the film and the cast body in example 1.

[0054] Below is physical data for the open porous polymer materials,according to examples 1 and 2 respectively, presented: Example 1 Example2 Weight (dry sample body)  1.75 g  1.32 g Weight (wet sample body)20.13 g 20.04 g Volume (estimated) 19.84 cm³ 19.82 cm³ Contained amountof water 18.38 g 18.72 g Density (g/cm³)  0.088  0.067 Density(estimated)  0.095  0.083 Porosity (%) 92.6 94.5

Example 3 Preparation of an Open Porous Polymer Material with CoupledBenzyl Penicillin

[0055] a) Preparation of a Polymer with Secondary OH-Groups

[0056] A pre-polymer was prepared by reacting polycaprolactondiole[M_(n)=530] with diphenylmetandiisocyanate (MDI) [NCO:OH]=2:1]. Apolymer (fibre polymer) was prepared by solving 30.46 g of thepre-polymer in 133.6 ml dimethyformamide (DMF), i.e. in 70% of the totalamount of DMF. The mixture was stirred under nitrogen gas until a clearsolution was obtained which took about 20 minutes. 2.7 g1.3diamino-2-hydroxypropane and 0.079 g dibutylamine were dissolved in57.3 ml DMF, i.e. in the remaining amount of DMF. Stirring of the solvedpre-polymer was increased and then the mixture of amine and DMF wasadded at once, and a substantial increase in viscosity was noted.

[0057] Prepared polymer “POL 4040? has 0.88 mmol secondary OH-groups pergram polymer.

[0058] The molecular weight of the polymer was estimated with SEC (SizeExclusion Chromatography) in DMF-LiCI against PEO standards and wasfound to be 68500.

[0059] b) Preparation of an Open Porous Polymer Material

[0060] The open porous polymer material was here prepared according toexample 1 b.

[0061] c) Coupling of Benzyl Penicillin to the Open Porous PolymerMaterial from Step b)

[0062] To 0.9 g of the product from step b) in the form of an openporous polymer material (so-called foam, here OH-polymer foam) 0.73 g(about 2 mmol) benzyl penicillin, 0.42 g (2.2 mmol) EDC-HCI (watersoluble carbodiimide), a catalytic amount of dimethylaminopyridine and10 ml distilled water, as solvent, were added. All that was added wentto solution and was soaked up by the open porous polymer material (theOH-polymer foam). The reaction was protected from light and was left forthree days, and then the open porous polymer material was washed withwater and ethanol several times before the polymer material was dried invacuum.

[0063] Sulphur analysis gave that 0.038 mmol OH-groups per gram polymer,in the form of an open porous polymer material, did bound benzylpenicillin, which corresponds to 12.4 mg benzyl penicillin per grampolymer.

[0064] A further example was performed where about 1 g of the productfrom example 1 in the form of an open porous polymer material was used,this example was otherwise principally identical with that describedimmediately above, i.e. to about 1 g of the product from example 1 inthe form of an open porous polymer material (a so-called foam, hereOH-polymer foam) 0.73 g (about 2 mmol) benzyl penicillin, 0.42 g (2.2mmol) EDC-HCI (water soluble carbodiimide), a catalytic amount ofdimethylaminopyridine and 10 ml distilled water, as solvent, were added.All that was added went to solution and was soaked up by the open porouspolymer material (the OH-polymer foam). The reaction was protected fromlight and was left for three days, and then the open porous polymermaterial was carefully washed with water and ethanol several timesbefore the polymer material was dried.

[0065] Sulphur analysis here gave that the polymer material contained0.146% by weight of sulphur, which corresponds to 1.46% by weight benzylpenicillin, and is equivalent to that 5% of the OH-groups of the polymermaterial have bonded benzyl penicillin.

[0066] The polymer material from the further example here in c) wascompared to an untreated polymer material, i.e. without coupled benzylpenicillin, in an “in vitro” test with a benzyl penicillin sensitivespecies of bacteria (Micrococcus luteus ATCC 9341). The polymer materialfrom this further example did show a cleared zone without any bacterialgrowth and in the untreated polymer material no influence on thebacteria could be observed.

1. A method for preparing an open porous polymer material, wherein saidmethod comprises forming of a polymer solution, addition of a porogen tosaid polymer solution and precipitation with water of a polymer fromsaid polymer solution, and said method then comprises removal of solventand porogen from said polymer material, characterized in that saidprecipitation is homogenous through that said water is in form ofcrystal water and-that said crystal water is bonded to said porogen,wherein said porogen is a sugar hydrate.
 2. A method for preparingaccording to claim 1, characterized in that a tixotropical mixture isformed at the addition of said sugar hydrate to said polymer solution.3. A method for preparing according to claim 1 or 2, characterized inthat said removal of solvent and porogen is achieved by using water. 4.A method for preparing according to any one of preceding claims,characterized in that said polymer is a polyurethane, polyurethaneureaor polyurea.
 5. A method for preparing according to any one of precedingclaims, characterized in that said sugar hydrate is a sugar monohydrate,for example glucose monohydrate or maltose monohydrate, or a sugardihydrate.
 6. A method for preparing according to any one of precedingclaims, characterized in that said polymer is biologically degradable.7. A method for preparing according to any one of preceding claims,characterized in that said polymer is biologically degradable bycontaining such an amount of ester groups that the polymer by hydrolysisor during enzymatic influence is degraded to such an extent that itlooses mechanical properties, is secreted or metabolised.
 8. A methodfor preparing according to any one of preceding claims, characterized inthat said method comprises design of the stabilised mixture, whichstabilised mixture is formed when said porogen with bonded crystal wateris added to said polymer solution.
 9. An open porous polymer material,characterized in that said polymer material has an open continuous porestructure and may be prepared by a method according to any one of claim1 to
 8. 10. An open porous polymer material according to claim 9,characterized in that said porous polymer material has an opencommunicating cell network.
 11. An open porous polymer materialaccording to claim 9 or 10, characterized in that said porous polymermaterial is homogenous and free from lumps as well as localprecipitations.
 12. An open porous polymer material according to any oneof claim 9 to 11, characterized in that said porous polymer material hasa rigid or stiff structure.
 13. An open porous polymer materialaccording to any one of claim 9 to 12, characterized in that said porouspolymer material has a total porosity of above 90%.
 14. An open porouspolymer material according to any one of claim 9 to 13, characterized inthat said porous polymer material may be of polyurethane,polyurethaneurea or polyurea.
 15. An open porous polymer materialaccording to any one of claim 9 to 14, characterized in that said porouspolymer material comprises secondary functional groups for covalentchemical bonding.
 16. An open porous polymer material according to anyone of claim 9 to 15, characterized in that said porous polymer materialcomprises a polymer with hydrolysable ester groups.
 17. A mixturecomprising said sugar hydrate and said polymer solution, characterizedin that said mixture is obtained at a method for preparing according toany one of claim 1 to
 8. 18. A designed material, characterized in thatsaid designed material comprises an open porous polymer materialaccording to any one of claim 9 to
 16. 19. A designed material accordingto claim 18, characterized in that the thickness of the material may bevaried from the thickness of a thin film to a thickness of up to 10 cm.20. Use of an open porous polymer material according to any one of claim9 to 16, or use of an open porous polymer material which is obtained ata method for preparing according to any one of claim 1 to 8,characterized in that said uses are as, for example, film, mouldedbodies, implants, pipes, or as filling in, for example, bones, such asdiscs, synthetic bone replacement, for example, in the form of granulesfor replacement of bone tissue, meniscus or the like, or as pipes, forexample, for replacement of blood vessels, guidance forgrowth/regeneration of tendons and/or nerves, or other biologicaltissue, or in connection with treatment of wounds as carrier ofdressings for wound healing, growth factors or the like, artificialskin, or as matrix/scaffold for, for example: stem cells, fibroblasts,osteoblasts, osteocytes, chondroblasts, chondrocytes among other, aswell as autogenous, allogenous and xenogenous, or as matrix/scaffold forgrowth/regeneration of tendons and/or nerves, or other biologicaltissue.
 21. Use of a designed material according to claim 18 or 19,characterized in that said designed material is used as, for example,film, moulded bodies, implants, pipes, or as filling in, for example,bones, such as discs, synthetic bone replacement, for example, in theform of granules for replacement of bone tissue, meniscus or the like,or as pipes, for example, for replacement of blood vessels, guidance forgrowth/regeneration of tendons and/or nerves, or other biologicaltissue, or in connection with treatment of wounds as carrier ofdressings for wound healing, growth factors or the like, artificialskin, or as matrix/scaffold, for example: stem cells, fibroblasts,osteoblasts, osteocytes, chondroblasts, chondrocytes among other, aswell as autogenous, allogenous and xenogenous, or as matrix/scaffold forgrowth/regeneration of tendons and/or nerves, or other biologicaltissue.
 22. Use of a mixture according to claim 17 for preparing adesigned material.